As a an automotive rearview assembly is equipped with more and more technical features (for example, laser-ablated openings in reflective layer(s) of a mirror element for delivery of light from a turning signal indicator to the user, or side blind zone indicators), the effective area of the mirror element that forms an image of space surrounding and at the back of the vehicle is consistently reduced. To counterbalance this at least to a certain degree, the idea of a complex transflective mirror element for use in an interior rearview assembly and in a driver-side exterior rearview assembly has been introduced, that facilitates the integration of various light sources (such as displays or turn signals) behind the mirror element without the substantially reduction of the area of the mirror.
In a case of a passenger-side exterior rearview mirror (which, in many cases, already possesses optical power and delivers to the driver an image, of an object behind the vehicle, that is smaller than the object as it would be seen directly with an naked eye), any additional reduction of the effective area of the mirror surface compromises the visibility and recognition of an image of the object. At it is preferred that both exterior rearview assemblies—on the driver's and passenger's sides—possess substantially similar optical and operational properties, and the continuous need to reduce the cost of the passenger's side exterior rearview assembly remains at odds with the use of an electrochromic element on the passenger's side, achieving an industrially reasonable tradeoff dictates the use of a mirror devoid of an electro-optical element in an exterior rearview assembly on the passenger's side of the vehicle. Accordingly, there remains a need in a single-substrate-based transflective mirror element adapted for use in operational conditions to which an exterior rearview assembly is exposed and, at the same time, characterized by transflective optical properties substantially matching those presented by electrochromic-element based rearview mirrors, without necessarily requiring an opening in a reflective layer, all achieved at a reduced cost.